Class JulianFields

The Julian Day is a standard way of expressing date and time commonly used in the scientific community.
It is expressed as a decimal number of whole days where days start at midday.
This class represents variations on Julian Days that count whole days from midnight.

The fields are implemented relative to EPOCH_DAY.
The fields are supported, and can be queried and set if EPOCH_DAY is available.
The fields work with all chronologies.

Field Detail

JULIAN_DAY

This is an integer-based version of the Julian Day Number.
Julian Day is a well-known system that represents the count of whole days since day 0,
which is defined to be January 1, 4713 BCE in the Julian calendar, and -4713-11-24 Gregorian.
The field has "JulianDay" as 'name', and 'DAYS' as 'baseUnit'.
The field always refers to the local date-time, ignoring the offset or zone.

For date-times, 'JULIAN_DAY.getFrom()' assumes the same value from
midnight until just before the next midnight.
When 'JULIAN_DAY.adjustInto()' is applied to a date-time, the time of day portion remains unaltered.
'JULIAN_DAY.adjustInto()' and 'JULIAN_DAY.getFrom()' only apply to Temporal objects that
can be converted into ChronoField.EPOCH_DAY.
An UnsupportedTemporalTypeException is thrown for any other type of object.

In the resolving phase of parsing, a date can be created from a Julian Day field.
In strict mode and smart mode
the Julian Day value is validated against the range of valid values.
In lenient mode no validation occurs.

Astronomical and Scientific Notes

The standard astronomical definition uses a fraction to indicate the time-of-day,
thus 3.25 would represent the time 18:00, since days start at midday.
This implementation uses an integer and days starting at midnight.
The integer value for the Julian Day Number is the astronomical Julian Day value at midday
of the date in question.
This amounts to the astronomical Julian Day, rounded to an integer JDN = floor(JD + 0.5).

MODIFIED_JULIAN_DAY

This is an integer-based version of the Modified Julian Day Number.
Modified Julian Day (MJD) is a well-known system that counts days continuously.
It is defined relative to astronomical Julian Day as MJD = JD - 2400000.5.
Each Modified Julian Day runs from midnight to midnight.
The field always refers to the local date-time, ignoring the offset or zone.

For date-times, 'MODIFIED_JULIAN_DAY.getFrom()' assumes the same value from
midnight until just before the next midnight.
When 'MODIFIED_JULIAN_DAY.adjustInto()' is applied to a date-time, the time of day portion remains unaltered.
'MODIFIED_JULIAN_DAY.adjustInto()' and 'MODIFIED_JULIAN_DAY.getFrom()' only apply to Temporal objects
that can be converted into ChronoField.EPOCH_DAY.
An UnsupportedTemporalTypeException is thrown for any other type of object.

This implementation is an integer version of MJD with the decimal part rounded to floor.

In the resolving phase of parsing, a date can be created from a Modified Julian Day field.
In strict mode and smart mode
the Modified Julian Day value is validated against the range of valid values.
In lenient mode no validation occurs.

RATA_DIE

Rata Die counts whole days continuously starting day 1 at midnight at the beginning of 0001-01-01 (ISO).
The field always refers to the local date-time, ignoring the offset or zone.

For date-times, 'RATA_DIE.getFrom()' assumes the same value from
midnight until just before the next midnight.
When 'RATA_DIE.adjustInto()' is applied to a date-time, the time of day portion remains unaltered.
'RATA_DIE.adjustInto()' and 'RATA_DIE.getFrom()' only apply to Temporal objects
that can be converted into ChronoField.EPOCH_DAY.
An UnsupportedTemporalTypeException is thrown for any other type of object.

In the resolving phase of parsing, a date can be created from a Rata Die field.
In strict mode and smart mode
the Rata Die value is validated against the range of valid values.
In lenient mode no validation occurs.